This invention relates to mobile rock crushing and screening plants. A portable rock crushing and screening processing plant is usually a collection of several units, each performing various material processing functions to prepare aggregate materials for use for, but not limited to, concrete and asphalt products. The various units can perform various stages of crushing, screening, conveying, and washing of aggregate and recycle materials. Portability is achieved by positioning the plants on towable or haulable modules, so that the plant can service multiple locations where processed materials can be produced.
Many plants have utilized a high vertical extent when fully deployed and it is often necessary to provide the ability to collapse the system, so as to meet highway height restrictions.
It has been know in the art to provide a folding and pivoting vibrating screen plant on a mobile platform. This has been done where the fines conveyor is directly coupled to the pivoting screen and moved forward along with the pivoting screen when the system is collapsed for transport. Other systems have utilized a fines conveyor fixed to the mobile frame and a rubber hopper disposed between the vibrating screen plant and the fines conveyor.
While both of these systems have enjoyed some commercial success in the industry, they both have drawbacks.
The system with the combined folding screen and fines conveyor can cause problems when the necessarily protruding fines conveyor is folded forward, thereby encroaching into space which is often needed for transferring material off the mobile platform. Additionally, the attached fines conveyor generally leads to use of a more expensive wider conveyor.
In the rubber hopper approach of the prior art, some of the screens were either lifted vertically without any forward pivoting and have resulted in limited height reduction or the need to partially disassemble inter-plant connections or the rubber was fixed at the bottom and pivoted, but resulting in leakage of fines material and the need for extra human involvement in the collapsing and raising process, to be certain that the hopper folds and unfolds optimally.
Consequently, there is a need for improvement in collapsible material processing equipment which eliminates leakage and extra labor without sacrificing space in front of the screen when folded forward, for the placement of transfer equipment.